my @other_stuff = split (' ', $words);

my @pairs = $string =~ /..?/sg;

   my @stuff = grep /\B$pairs[0]|\B$pairs[1]|\B$pairs[2]/, 
@other_stuff; 
# this assumes I know the word length. 
# but actually I would not know. 
# so this is not ok and needs to be fixed!


for (@stuff) { print $_ . " ";

print OUTPUT $_ . " ";

 }

close OUTPUT; 

exit;